Chi is a genetic element that promotes recombination of lambda via the RecB pathway of E. coli. We will ascertain whether Chi promotes the formation or the resolution of "figure-8's" (Holliday structures). "Figure-8's" formed in vivo in the presence of enzymes (RecA and RecBC) required for Chi activity will be packaged in their absence. The inverse experiment will also be attempted. Chi activity will be monitored as the frequency of recombinants in Chi-containing interval relative to that in a control interval.